thumb|Welbore Ellis, 1st Baron Mendip
Viscount Clifden, of Gowran in the County of Kilkenny, Ireland, was a title in the Peerage of Ireland. It was created on 12 January 1781 for James Agar, 1st Baron Clifden. He had already been created Baron Clifden, of Gowran in the County of Kilkenny, in 1776, also in the Peerage of Ireland. The Viscounts also held the titles of Baron Mendip in the Peerage of Great Britain from 1802 to 1974 (a title which is still extant and now held by the Earl of Normanton) and Baron Dover from 1836 to 1899, when this title became extinct, and Baron Robartes from 1899 to 1974, when this title became extinct, the two latter titles which were in the Peerage of the United Kingdom. The interrelated histories of the peerages follow below.
Viscount Clifden
James Agar, 1st Viscount Clifden was the son of Henry Agar of Gowran Castle and the elder brother of Charles Agar, 1st Earl of Normanton. His mother was Anne Ellis, daughter of Welbore Ellis, Bishop of Meath, and sister of the politician Welbore Ellis, who in 1794 was created Baron Mendip in the Peerage of Great Britain with remainder to his three nephews Lord Clifden, the future Lord Normanton and another brother of theirs. Lord Clifden was succeeded by his son, the second Viscount. He represented County Kilkenny in the Irish House of Commons and Heytesbury in the British House of Commons.
In 1802, he succeeded his great-uncle Welbore Ellis, 1st Baron Mendip as second Baron Mendip according to the special remainder, and in 1804 assumed by royal license the additional arms and surname Ellis.
Baron Mendip
thumb|George Agar-Ellis, 1st Baron Dover
The title of Baron Mendip, of Mendip in the County of Somerset, was created in the Peerage of Great Britain in 1794 for the politician Welbore Ellis, with remainder to the three eldest sons of his sister Anne Ellis, wife of Henry Agar (which included James Agar, 1st Viscount Clifden and Charles Agar, 1st Earl of Normanton). Lord Mendip died childless and was succeeded according to the special remainder by his great-nephew the second Viscount Clifden, who became the second Baron Mendip as well.
Baron Dover
The title of Baron Dover, of Dover in the County of Kent, was created in the Peerage of the United Kingdom in 1831 for the Whig politician the Hon. George Agar-Ellis, only son of the second Viscount Clifden. Agar-Ellis represented Heytesbury, Seaford, Ludgershall and Okehampton in the House of Commons and served under Lord Grey as First Commissioner of Woods and Forests from 1830 to 1831. On Lord Dover's early death in 1833, the title passed to his eldest son, the second Baron. In 1836 he also succeeded his grandfather as third Viscount Clifden.